The purpose of this core is to support a program project designed to assess the effects of bedrest in elderly individuals on insulin resistance and muscle loss. The charge of this core is three-fold: to provide mass spectrometry analysis, statistical analysis, and data management. This program project entails the utilization of stable isotope tracer methodology to determine amino acid, glucose, and fatty acid kinetics. Therefore, a major goal of this core will be to provide mass spectrometry analyses. Due to the complex nature of these study designs and their primary endpoints, extensive statistical analysis is warranted. Thus, a second goal of this core will be the provision of statistical analysis and the expertise to perform and interpret multifaceted statistical outcomes. Finally, this program project is expected to generate a large volume of data that must be carefully stored and managed. Thus, a third goal of this core will be to provide data handling, management, storage, and quality control for the program project. To achieve these goals, the Analytical Core will pursue the following specific aims: (1) Provide accurate sample analysis of isotopic enrichment; assistance in planning experiments using stable isotope tracers; and consolidation of the analysis of stable isotope tracers to ensure quality control and uniformity of results; and (2) provide data handling, storage, and quality control; statistical analyses to handle experimental variability; and data consolidation and presentation for the Data and Safety Monitoring Board. We have developed a data base system whereby data can be stored and subsequent queries and consolidated results can be obtained. This data management system will be of value to each individual project, as well to the DSMB to assist in its oversight of subject safety. Housed at the University of Texas Medical Branch (UTMB), the Analytical Core will provide a critical link between sample analysis, data analysis, and data archiving.